Excavation tool assembly

ABSTRACT

The invention relates to an excavation tool assembly comprising a housing having a base and an excavation tool having a tool shaft connected to the assembly and extending downwards from the base at an angle, the assembly further comprising a connector portion for attachment to a mechanical power source.

This invention relates generally to the field of excavation, and inparticular includes excavation for the purposes of creating trenches andcavities for underpinning structures, for example for reinforcingfoundations of buildings and the like.

Subsidence is a common problem affecting buildings and other suchstructures. Displacement and movement of earth on which structures arebuilt can occur for a variety of reasons. Common reasons are thebuild-up of excessive groundwater causing softening of the earth, thedrying out of earth leading to shrinkage and so forth.

Subsidence commonly manifests itself by the slippage of foundationsbelow ground level, leading to movement of the structure above, possiblyresulting in cracks appearing in the walls and in extreme circumstancesfailure of the structure.

The effects of subsidence can be mitigated by taking the remedial actionof underpinning the structure, commonly underpinning the foundationsbelow ground level. Various methods of underpinning are routinelyemployed.

One method involves excavating a trench adjacent the structure (or arelevant portion of the structure). The trench often extends below thelevel at which the foundations terminate. It is then necessary toexcavate a cavity directly below the foundation down to firm strata. Thecavity can then be filled with a suitable material which replaces theexcavated earth and will act to bridge the gap between the foundationand firm strata, thus supporting the weight of the foundation andreinforcing the foundation from below. The cavity can be filled withconcrete, but other suitable materials can be used. The underpinning isusually performed by sequentially excavating sections or bays below thefoundations so that the foundations are at all times throughout theprocess fully supported and the foundations are thus graduallyunderpinned in stages.

Often, in the case of very large structures, supporting pillars can beintroduced into the cavity, such pillars can be made of steelfibre-reinforced concrete, steel or other suitable material.

Another method involves introducing or casting reinforced concrete beamsinto a pocket created in an existing structure below ground level butabove the level at which the existing foundations terminate. Each beamcan then be supported by pillars or piles driven into the earth belowthe exiting foundations and down to firm strata. Each beam is typicallysupported by two piles one either side of the existing structure,although variations exist wherein two piles can be driven on the sameside and the beam forms a cantilever which supports the existingstructure.

Whichever method is used, there is a necessity to excavate a hole ortrench adjacent to a portion of the structure to be underpinned. Whereit is necessary to create cavities below the foundations, it is commonlynecessary to excavate below the level of the existing foundation andextend laterally underneath. Excavating in this manner is difficult toachieve with machine-based tools due to the inconvenience of thelocation and angles necessary for correct operation.

As a consequence, it is typically necessary for trenches and cavities tobe dug, at least in part, manually by laborers. The laborers areconsequently positioned in the trench and lateral excavation work todefine the cavities must be carried out by hand.

This type of manual excavation has a number of drawbacks. The work canbe slow and time-consuming, thus increasing costs. Furthermore, there isincreased danger associated with such manual work. For example, theearth underneath structures requiring underpinning is often unstable andthere is an increased risk of collapse of cavities which can endangermanual laborers.

There is therefore a need for alternative tools and methods forexcavation which allows such trenches and cavities to be created bymachine operated from the ground level, thus avoiding the need formanual laborers. As such, the excavation process can be speeded up,reducing costs as well as increasing safety for workers.

It is an object of the present invention to overcome or at leastmitigate at least some of the problems inherent in such prior art toolsand methods.

According to a first aspect of this invention there is provided anexcavation tool assembly comprising a base and an excavation tool havinga tool shaft connected to the assembly and extending downwards from thebase at an angle, the assembly further comprising a connector portionfor attachment to a mechanical power source.

The tool shaft can be set at an angle relative to the assembly base suchthat mechanical power can be transmitted through the angle to a tool,which tool can then be operated below ground level for excavationpurposes. Such an angle can be created by many different methods. Forexample, an angle could be created by welding, bolting, screwing etc thetool to the assembly base in a manner which creates a fixed downwardangle. Persons skilled in the art will immediately appreciate that thereare many means by which such an angle could be created.

The introduction of a downward angle between the tool shaft and theassembly base allows an excavation tool to be used to create trenchesand cavities by operation of the tool from ground level, particularly inthe process of underpinning structures as described above. It will beappreciated that the angle dimension will vary depending upon theparticular requirements of the excavation task to be carried out. Thiswill be dictated, for example, by the depth of the excavation relativeto the ground level and so on.

Thus, according to a first aspect of this invention the device allowstrenches and cavities to be excavated by machine operating at, or nearto ground level, and avoids the need for manual laborers to excavatemanually and enter the resulting trench to undertake further excavationwork with attendant savings in both time and cost, as well as decreasein danger for operators.

The excavation tool can be removable from the assembly. Thus, variousdifferent tool types can be sequentially coupled to the assemblypermitting a range of different excavation operations to be undertakenin a rapid and convenient manner.

The tool can be securable to the assembly by tool locking means,allowing precise orientations of the tool to fixed relative to theassembly and preventing unwanted movement of the tool, particularlyduring delicate excavation operations.

The tool locking means can be provided in an elongate receptacle formingpart of the base of the assembly. Thus, for example, the tool shaft canbe insertable into a receptacle in a complementary fashion and can befastened therein.

The tool can be rotatable about its longitudinal axis and securable in afixed position relative to the base of the assembly and/or thereceptacle can be rotatable about its longitudinal axis and securable ina fixed position relative to the base of the assembly. As such, the toolcan be securely positioned relative to the base in a manner which allowsthe head of the tool to be set in any desired position allowingsignificant versatility in the operation of the tool for excavation.Rotation of the tool or receptacle can be achieved by manual means or byautomated means. This can provide yet further advantages when it isdesired to excavate in awkward positions or locations.

The tool shaft can comprise two sections, a first section connected tothe assembly and a second section bearing a tool head and connected tothe first section by a movable joint. Furthermore, the second sectioncan be movable to a position perpendicular to the first section. Suchembodiments can provide a superior degree of flexibility with regard tothe angles at which excavation work can be carried out.

The assembly can be attached to a mechanical power source by anintermediate connector such as a quick hitch device (a term of art).Quick hitch devices are well known to persons skilled in the art andallow tools of choice to be attached, in a bespoke manner, to aswing-arm/boom of a mechanical excavator or other similar device. Suchintermediate connectors provide an additional degree of flexibility withrespect to the types of mechanical power source which could be attachedto the assembly.

In all embodiments of the above-described excavation tool assemblies,the excavation tool assembly can be an underpinning tool assembly andthe excavation tool can be an underpinning tool. Thus, the assembly canbe specifically adapted for the purposes of excavating trenches,channels, ditches, conduits and the like which will be used in thecreation of structural support for foundations in buildings and thelike. Here the underpinning excavation work can extend to below groundlevel.

In one particular embodiment, the elongate receptacle is integral withthe base, the excavation tool is a removable underpinning tool, the toolis lockable into the receptacle by locking means which are provided inthe elongate receptacle and the tool is rotatable about its longitudinalaxis and securable in a fixed position relative to the base of theassembly. The connector portion can be attached to a swing-arm of amechanical excavator by a quick hitch device.

In another aspect of the invention there is provided an excavation toolfor use with any of the above-described tool assemblies. The toolcomprises a shaft portion and a head portion and means for coupling thetool to the assembly.

In yet another aspect, the invention also provides a method ofexcavating comprising using the above-described assemblies. For example,the method may comprise excavating a trench adjacent to and/orunderneath a portion of a structure to be underpinned. In this way, acavity can be formed directly adjacent to or below the structure to beunderpinned (for example a domestic property or the like) whichstructure can then be reinforced by introducing reinforcing means intothe cavity. Such reinforcing means can include concrete, reinforcedconcrete, steel and other suitable materials.

A simple stylized embodiment of the invention will now be described, byway of example only, with reference to the accompanying drawings inwhich FIG. 1 depicts a stylized excavation tool coupling device, FIG. 2depicts a stylized excavation tool coupling device with reference to atrench and FIG. 3 depicts an excavation tool for use with the excavationtool coupling device.

Referring to FIG. 1, depicted in stylized isometric view is anexcavation tool assembly which comprises a base (11) to which a shaft(12) of a tool (13) is connected, and in which the assembly furthercomprises a connector portion (14) for attaching a mechanical powersource.

The tool has a head portion which can be in the form of any structuresuitable for performing excavation functions. The shaft of the tool canbe provided as any suitable elongate structure, such as a cylinder.

The connector portion (14) comprises means for connecting a mechanicalpower source to the assembly. Such means are intended to physicallyattach the power source to the assembly. Any suitable means can beemployed. For instance, screws, bolts etc. In embodiments which furthercomprise an intermediate connector such as a quick hitch device, thepower source is connected indirectly to the connector portion via theintermediate connector.

In embodiments having tool locking means, the shaft of the tool can befixed in a plurality of positions relative to the base of the assemblysuch that the shaft of the tool can be rotated to the desired locationand fixed in position. Any suitable locking means can be provided, suchas a nut and bolt arrangement, a pin for insertion though aligned holesin both shaft and receptacle and so on. Persons skilled in the art willbe familiar with such arrangements. Rotation of the tool can also beachieved by automated means using motors, hydraulics and the like. Theskilled person would readily appreciate how to implement such automatedmeans.

In certain embodiments the tool (and/or an elongate receptacle whichaccepts the tool) is rotatable about its longitudinal axis and can befixed relative to the assembly base. Persons of skill in the art willappreciate that such a flexible coupling between the tool or receptacleand the base can be created by any suitable means. For example, the toolor receptacle could be provided with teeth which interdigitate withcorresponding teeth or recesses provided on the assembly base. The toolor receptacle could then be rotated to any desired location relative tothe coupling portion and locked in place by any suitable means such asbolts or screws or the like.

Referring to FIG. 2, a stylized view of the assembly is depicted. A base(21) is shown attached to the shaft (22) of the tool (23). The assemblyis depicted at ground level (24) adjacent to a trench (25) which trenchis depicted adjacent to a portion of a structure (26). The longitudinalaxis of the tool shaft (27) can be set at a downward angle θ relative tothe longitudinal axis (28) of the base (21), such that mechanical powercan be transmitted through an angle θ. The angle can be of any dimensionappropriate for the desired orientation of the tool in order to performthe required excavation function.

FIG. 3 depicts a side view of an assembly attached to a swing arm of amechanical excavator (not shown). At one end of the swing arm (31) is abucket portion (32). Attached to the bucket portion (32) is anintermediate connector such as a quick hitch device (33) which is inturn attached to an excavation tool assembly (34) having a base portion(35). A tool (37) is attached to the base portion (35) via a lockingmechanism (38). The assembly is depicted at ground level (39) adjacentto a trench (300) which trench is depicted adjacent to a portion of astructure (301).

The excavation can be performed for the purposes of underpinning astructure. In such cases, the tools used will be underpinning tools andthe assembly is an excavation tool assembly. In some embodiments, suchas that depicted in FIG. 3, the base comprises an elongate receptacle(36) which is integral with or otherwise permanently attached to thebase (35) such as by welding. The base (35) is attached to the quickhitch device by any suitable means such as bolts, screws and so on, orit can even be permanently attached by means such as welding. The shaftof the tool (37) is secured to the receptacle (36) by any suitablelocking means such as bolts or screws, extending through the receptacle(36) and into the shaft of the tool (37).

The term “excavation”, is intended to encompass any activity related tothe construction of structures such as trenches, cavities, holes,ditches, pits, elongate channels, conduits, pockets, recesses, caves andso on. Such excavations can be created below or adjacent a structure(for example the foundation of a wall).

The term “underpinning” is well known in the art.

An “excavation tool” for use with the assembly of the invention isenvisaged to be any tool suitable for carrying out any type of activityassociated with the creation of the above-described structures. Suchtools include but are not limited to knifes, chisels, cutters, bolsters,diggers, buckets, spades, scrapers and so on.

The term “mechanical power source” is intended to encompass any suitablemachine which can act as a source of power suitable for creating suchexcavation structures. Typical power sources will be swing-armmechanical excavators, piledrivers, jack-hammers and the like.

1. An excavation tool assembly for excavating a cavity below a structureto be underpinned, the assembly comprising: a base having a connectorportion for attaching the assembly to a source of mechanical power; anexcavation tool comprising a tool shaft having a longitudinal axisextending between a first end connected to the base, and a second end towhich a tool head is mounted; the assembly being configured such that inuse when the tool head is brought into contact with a side face of earthto be excavated below the structure, the first end of the tool shaft isdisposed so as to be spaced generally laterally from and above thesecond end of the tool shaft, and wherein the excavation tool isrotatable about the longitudinal axis and securable in a fixed positionrelative to the base.
 2. An assembly according to claim 1 wherein theexcavation tool is removable from the assembly.
 3. An assembly accordingto claim 2 wherein the tool is securable to the assembly by tool lockingmeans.
 4. An assembly according to claim 3 wherein the tool lockingmeans are provided in an elongate receptacle.
 5. An assembly accordingto claim 4 wherein the receptacle is rotatable about its longitudinalaxis and securable in a fixed position relative to the base of theassembly.
 6. An assembly according to claim 1 wherein the tool shaftcomprises two sections, a first section connected to the base and asecond section bearing the tool head and connected to the first sectionby a movable joint.
 7. An assembly according to claim 6 wherein thesecond section is movable to a position perpendicular to the firstsection.
 8. An assembly according to claim 1 wherein the assembly can beattached to a mechanical power source by an intermediate connector suchas a quick hitch device.
 9. An assembly according to claim 4 wherein theelongate receptacle is integral with the base, and wherein theexcavation tool is an underpinning tool, and wherein the connectorportion is attached to a swing-arm of a mechanical excavator by a quickhitch device.
 10. A method of underpinning a structure comprisingexcavating underneath a portion of a structure to be underpinned to forma cavity directly below the structure and reinforcing the portion byintroducing reinforcing means into the cavity, characterized in thatsaid excavating comprises excavating a trench adjacent to a portion ofthe structure to be underpinned and further comprises excavatingunderneath a portion of the structure to be underpinned using theassembly of any preceding claim.
 11. The method of claim 10 wherein thestructure to be underpinned is a domestic property or the like.